• Korean Journal of Fisheries and Aquatic Sciences
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• v.53 no.5
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• pp.752-760
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• 2020

Acute hepatopancreatic necrosis disease (AHPND), previously known as early mortality syndrome (EMS), is an emerging disease in shrimp caused by Vibrio parahaemolyticus. Some V. parahaemolyticus strains are associated with foodborne diseases in humans. To date, studies on the relationship between AHPND and pathogenic V. parahaemolyticus are very limited. In this study, we monitored the thermostable direct hemolysin-related hemolysin (trh) gene and AHPND-related genes, such as Photorhabdus insect-related (pir) genes, in 892 strains of V. parahaemolyticus isolated and identified in 24 areas of the West Coast of Korea from May to October 2019. The trh gene was detected in 9.6% of the isolates from short neck clam samples. However, the pirA and pirB genes related to AHPND were not found in any of the isolates despite using both duplex and nested PCR assays, suggesting that AHPND-related genes were nonexistent in the V. parahaemolyticus strains isolated. This study contributes to the current understanding of the relationship between AHPND and V. parahaemolyticus in Korea, as well as provides data on spatial and seasonal distributions of V. parahaemolyticus.

• Korean Journal of Fisheries and Aquatic Sciences
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• v.54 no.5
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• pp.691-697
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• 2021

Vibrio parahaemolyticus associated with acute hepatopancreatic necrosis disease (Vp_AHPND) and Enterocytozoon hepatopenaei (EHP) are the two most important pathogens in shrimp aquaculture and they have caused enormous losses to the shrimp industry worldwide. In ponds, the major target organ for the two pathogens is the hepatopancreas, and infection with EHP is a known potential risk factor for Vp_AHPND infection. This study aimed to develop a PCR (polymerase chain reaction)-based diagnostic method for simultaneously detecting Vp_AHPND and EHP. The newly developed PCR diagnostic method could be used to test various samples, such as seawater, shrimp, and feces. The diagnostic method exhibited high sensitivity and specificity for both pathogens. This will help reduce the potential economic losses that may have been caused by the two major shrimp pathogens, Vp_AHPND and EHP, and will allow for the efforts and time spent combatting them to be dedicated elsewhere.

• Journal of fish pathology
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• v.28 no.1
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• pp.1-7
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• 2015

In 2009 outbreaks of an emerging disease in shrimp farms were first reported in China. The disease was known as early mortality syndrome (EMS), or acute hepatopancreatic necrosis disease (AHPND). Since 2009, the disease has been spread to Vietnam, Malaysia, Thailand and Mexico. The causative agent of the disease was identified as Vibrio parahaemolyticus. It is a common seawater inhabitant bacterium, and the pathogen can sometimes contaminate seafood. The disease has caused mass mortality of cultivated shrimp, and huge economic losses in the countries named above. In order to prevent the introduction and establishment of AHPND, emergency measures, such as strengthening of import conditions and even import bans, were put in place by many other countries. In Korea, on the other hand, there are large quantities of shrimp imports from countries, such as Thailand and Vietnam. Transportation of live and fresh dead shrimp is highly likely, and could be a transmission pathway if the shrimp are sourced from populations in AHPND endemic areas. It is important to recognize that importing countries may provisionally adopt sanitary or phytosanitary measures on the basis of available pertinent information, including that from the relevant international organizations, as well as from sanitary or phytosanitary measures applied by other countries based on "Agreement on Application of Sanitary and Phytosanitary Measures". It is pertinent that Korea also takes proper emergent measures to keep out diseases and provide safe seafood.

• Korean Journal of Fisheries and Aquatic Sciences
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• v.56 no.1
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• pp.133-139
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• 2023

The advantage of biofloc technology (BFT) in aquaculture is in the prevention of pathogenic transmission. In this study, we performed an investigation on viral, bacterial, and microsporidian parasite infections targeting a total of 194 whiteleg shrimp Litopenaeus vannamei reared in seven BFT-farms on the west coast of Korea in 2021. Hepatopancreatic and cuticular epithelium and pereiopods tissues of shrimp were tested for the four pathogens, Enterocytozoon hepatopenaei (EHP), Vibrio parahaemolyticus causing Acute Hepatopancreatic necrosis disease (VP_AHPND), white spot syndrome virus (WSSV), and hepatopancreatic parvovirus (HPV). The microsporidian parasite EHP was detected in the hepatopancreatic tissue of BFT whiteleg shrimp in the Ganghwa region, whereas no other pathogenic bacteria or virus was detected on the shrimp in the seven BFT-farms. As a result of bacterial flora in the rearing water of BFT whiteleg shrimp using DNA microbiome technology, V. chemaguriensis and V. alfacsensis were contained at 0.05% and 0.01%, respectively, but no VP_AHPND was detected. These findings will serve as a basis for supporting safe BFT-aquaculture of whiteleg shrimp.

• Korean Journal of Fisheries and Aquatic Sciences
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• v.54 no.5
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• pp.698-702
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• 2021

Yellow head virus (YHV) is a rod-shaped positive-sense single-stranded RNA virus, classified into the genus Okavirus, family Roniviridae, and order Nidovirales. In this study, 200 fleshy prawns (Fenneropenaeus chinensis) collected from the vicinity of Narodo in Goheung-gun, Korea, were screened for the presence of yellow head complex viruses and related genotype such as YHV genotype 8. The detection rate of YHV genotype 8 among the 200 fleshy prawns, determined using nested RT-PCR (reverse transcription polymerase chain reation), was 39.0%. Phylogenetic analysis of the ORF1b gene of YHV showed that eight distinct genetic lineages were detected. The four strains of YHV genotype 8 obtained in this study formed a robust clade with the YHV genotype 8 group that was first isolated from fleshy prawns in China suspected to have acute hepatopancreatic necrosis disease (AHPND).